The present invention is directed to speech identification systems and more particularly to a binary system, based on autocorrelation techniques, for converting known speech segments into storage coefficients which can be compared against unknown received speech segments for recognition or verification purposes.
In communication, data processing and control systems, it is desirable to utilize speech as a direct input for commands, e.g., to activate machine functions in computers, automatic teller machines and the like. Because of the complex nature of speech, its considerable variability from speaker to speaker and from time-to-time for the same speaker it is difficult to attain reliable recognition of speech segments.
A number of systems have been developed for correlating segments of a bit stream--one such system is described in U.S. Pat. No. 4,071,903 entitled, "Autocorrelation Function Factor Generating Method and Circuitry Therefor" by S. M. Head, et al. In that patent, a bit stream is directed along two paths, one providing an N bit delay and the other an M-bit delay. The most recent received bit is correlated with the delayed bits and the product is applied to a bidirectional digital counting circuit to form an autocorrelation function factor.
Another system of interest is disclosed in U.S. Pat. No. 4,161,625, entitled, "Method for Determining the Fundamental Frequency of a Voice Signal" by H. Katterfeldt et al. The system of that patent uses two shift registers, each providing different time delays to an input signal for providing inputs to a coincidence circuit. The output from the coincidence circuit drives a counter to provide correlation coefficients which identify speech fundamental frequencies.
Additional patents of interest are U.S. Pat. No. 4,227,175, entitled "Data Recognition Apparatus" by E. L. Newman, and U.S. Pat. No. 4,015,088, entitled "Real-Time Speech Analyzer" by V. V. Dubnowski, et al.
A publication of interest is: R. F. Purton, Speech Recognition Using Autocorrelation Analysis (June 1968), IEEE Transactions on Audio and Electracoustics, Vol. AV-16, No. 2, pp. 235-239.